Okay, we are given 7844 and 8544. Let's add them up step by step.

Step 1: We'll start by adding the digits 4 & 4 in column 1 and get 8.

Step 2: We'll start by adding the digits 4 & 4 in column 2 and get 8.

Step 3: We'll start by adding the digits 8 & 5 in column 3 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 7 & 8 in column 4 and get 16.
We'll write down the last digit 6 and carry the 1 to the next column.

So, 7844 + 8544 = 16388.

